The present invention relates to a distributed search method for finding lost assets.
Communication infrastructures suitable for mobile users (in particular, though not exclusively, Public Land Mobile Networks, PLMN, in the form of cellular radio infrastructures) have now become widely adopted. Whilst the primary driver has been mobile telephony, the desire to implement mobile data-based services over these infrastructures, has led to the rapid development of data-capable bearer services across such infrastructures. This has opened up the possibility of many Internet-based services being available to mobile users.
Data-capable bearer services can be provided, for example, by a Short Message Service (SMS), by using a voice traffic circuit for data, or by using specialised data facilities such as provided by GPRS for GSM PLMNs (GPRSxe2x80x94General Packet Radio Servicexe2x80x94enables IP (or X.25) packet data to be sent through the PLMN and full details of GPRS can be found in the ETSI, European Telecommunications Standards Institute, GSM 03.60 specification).
A number of technologies also exist for the short range wireless communication of information to and between mobile devices. These technologies include infra-red based technologies and low-power radio technologies (including, in particular, the recent xe2x80x9cBluetoothxe2x80x9d short range wireless standard). Depending on the technology implementation, differing types of message propagation will be enabled including asynchronous message broadcast, and multicast and point-to-point duplex connections established after coordination and negotiation between communicating devices.
The increasingly widespread deployment of the foregoing technologies in mobile devices has led to an increased interest in ways of determining the location of mobile devices, primarily with a view either to providing user-location information to emergency services or to enabling the provision of location-aware information services. A number of methods exist for determining the location of a mobile user as represented by an associated mobile equipment. Some of these methods, such as the use of a GPS (global positioning system) system described below relation to FIG. 1, result in the user knowing their location thereby enabling them to transmit it to a location-aware service they are interested in receiving; other of the methods, such as the use of a PLMN location server described below in relation to FIG. 2, result in the user""s location becoming known to a network entity from where it can be supplied directly to a location-aware service (generally only with the consent of the user concerned).
More particularly, on the left-hand side of FIG. 1, a mobile entity 11A is provided with a standard GPS module and is capable of determining the location of entity 11A by picking up signals from satellites 12. The entity 11A can then supply this location when requesting, in request 61, a location-aware service from service system 40. The right-hand side of FIG. 1 depicts, in relation to mobile entity 11B, two ways in which assistance can be provided to the entity in deriving location from GPS satellites. Firstly, a PLMN 10 can be provided with fixed GPS receivers 13 that each continuously keep track of the satellites 12 visible from the receiver and pass information in messages 63 to local mobile entities 11B as to where to look for these satellites and estimated signal arrival times; this enables the mobile entities 11B to substantially reduce acquisition time for the satellites and increase accuracy of measurement. Secondly, as an alternative enhancement, the processing load on the mobile entity 11B can be reduced and encoded jitter removed using the services of network entity 14 (in or accessible through PLMN 10). Once the mobile unit 11B has determined its location, it can pass this information in request 65 when invoking a location-aware service provided by service system 40.
FIG. 2 depicts two general approaches to location determination from signals present in a cellular radio infrastructure. First, it can be noted that in general both the mobile entity and the network will know the identity of the cell in which the mobile entity currently resides, this information being provided as part of the normal operation of the system. (Although in a system such as GSM, the network may only store current location to a resolution of a collection of cells known as a xe2x80x9clocation areaxe2x80x9d, the actual current cell ID will generally be derivable from monitoring the signals exchanged between the BSC 14 and the mobile entity). Beyond current basic cell ID, it is possible to get a more accurate fix by measuring timing and/or directional parameters between the mobile entity and multiple BTSs 15, these measurement being done either in the network or the mobile entity (see, for example, International Application WO 99/04582 that describes various techniques for effecting location determination in the mobile and WO 99/55114 that describes location determination by the mobile network in response to requests made by location-aware applications to a mobile location centerxe2x80x94serverxe2x80x94of the mobile network).
The left-hand half of FIG. 2 depicts the case of location determination being done in the mobile entity 11C by, for example, making Observed Time Difference (OTD) measurements with respect to signals from BTSs (Base Transceiver Stations) 15 and calculating location using a knowledge of BTS locations. The location data is subsequently appended to a service request 66 sent to service system 40 in respect of a location aware service. The calculation load on mobile entity 110 could be reduced and the need for the mobile to know BTS locations avoided, by having a network entity do some of the work. The right-hand half of FIG. 2 depicts the case of location determination being done in the network, for example, by making Timing Advance measurements for three BTSs 15 and using these measurements to derive location (this derivation typically being done in a unit associated with BSC, Base Station Controller, 16). The resultant location data is passed to a location server 17 from where it can be made available to authorised services. When the mobile entity 11D of FIG. 5 wishes to invoke a location-aware service available on service system 40, it sends a request 69 including an authorisation token and its ID (possible embedded in the token) to the service system 40; the service system then uses the authorisation token to obtain the current location of the mobile entity 11D from the location server 17. The service system 40 can be pre-authorised to access the location server 17.
The possibility of using the locatability of mobile devices to provide security systems has been proposed. Thus U.S. Pat. No. 5,712,679 describes a vehicle security system in which a vehicle is provided with a locatable portable electronic camera which, when triggered by unauthorized activity, takes a picture and stores it with location data; at the same time it sends the picture and location data back to a remote receiver where the location data is displayed on a map display and the picture on a TV display.
It has also been proposed to geographically route messages to mobile devices. The paper xe2x80x9cGeographic Addressing, Routing and Resource Discovery with GPSxe2x80x9d (Tomasz Imielinski and Julio C. Navas; Computer Science Department, Rutgers, The State University Piscataway, N.J.) describes various geographic routing applications including geographic email, geographic broadcasting, and geographically directed multicasting, for example, to all police cars in a specified area.
It is an object of the present invention to provide a distributed search method for finding lost assets that utilizes certain capabilities of mobile devices equipped both with mobile radio communication means and short-range wireless transceivers.
According to one aspect of the present invention, there is provided a method of searching for a lost asset provided with a short-range wireless transceiver operative to respond to receipt of an enquiry transmission including an identifier of the asset, the method comprising the steps of:
(a) sending out from a finder service a search request including the identifier of a lost asset, this request being sent over a mobile radio infrastructure to a plurality of mobile entities each equipped both with a radio transceiver for communicating with the infrastructure and with a short-range wireless transceiver;
(b) locally transmitting from mobile entities that have received the search request, a search enquiry incorporating the lost-asset identifier, this enquiry being transmitted using the short-range wireless transceivers of the mobile entities;
(c) upon a mobile entity receiving back a response from the lost asset, returning a found message over the mobile radio infrastructure to the finder service, this response either including location data concerning the whereabouts of the lost asset or enabling such data to be obtained by the finder service.
According to another aspect of the present invention, there is provided a mobile device comprising:
a radio subsystem for sending and receiving messages using a mobile radio infrastructure;
a short-range wireless transceiver; and
a control subsystem operative upon receipt, by the cellular radio subsystem, of a search-request message including the identifier of a lost asset, to cause the short-range wireless transceiver to transmit a local search enquiry incorporating the lost-asset identifier, the control subsystem being further operative, upon the short-range wireless transceiver receiving back a response from the lost asset, to cause the cellular radio subsystem to the return a found message over the mobile radio infrastructure, this found message either including location data concerning the whereabouts of the lost asset or enabling such data to be obtained by the finder service.